fix: bump Node.js to 20 for Docusaurus build

Author: MDUYN

.github/workflows/deploy-docs.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: '18'
+          node-version: '20'
           cache: 'npm'
           cache-dependency-path: docusaurus/package-lock.json